The present paper presents the results of an extensive electron microscopy investigation on the decomposition modes of high temperature austenite in 9Cr–W–V–Ta reduced activation ferritic–martensitic steels. Although the displacive martensitic transformation is predominant on austenitisation, low volume fraction of Fe rich M3C or M23C6 precipitates formed, when the tungsten content exceeded 1 wt-. The compositional inhomogeneity introduced in the austenite by the nature, chemistry and kinetics of dissolution of the pre-existing carbides is dependent on the steel composition and austenitisation conditions. The extent of repartitioning of tungsten between M23C6 and ferrite largely influences the kinetics of austenite and martensite transformation, for the same austenitisation conditions. Supporting evidence from calorimetry analysis is also presented.
In the present work, gold (Au), silver (Ag), and copper
(Cu) based
mono- and bimetallic NPs are prepared using a cost-effective facile
wet chemical route. The pH for the synthesis is optimized in accordance
with the optical spectra and supported by the finite difference time
domain simulation studies. FESEM and TEM micrographs are used to analyze
the morphology of the prepared nanoparticles. TEM images of bimetallic
nanoparticles (BMPs) verified their bimetallic nature. XRD studies
confirmed the formation of fcc-structured mono- and bimetallic NPs.
Photoluminescence studies of the as-synthesized NPs are in good agreement
with the previous publications. These synthesized NPs showed enhanced
catalytic activity for the reduction/degradation of 4-nitrophenol,
rhodamine B, and indigo carmine dyes in the presence of sodium borohydride
(NaBH
4
) compared to NaBH
4
alone. For the reduction
of 4-nitrophenol, Au, Cu, and CuAg nanoparticles exhibited good catalytic
efficiency compared to others, whereas for the degradation of rhodamine
B and indigo carmine dyes the catalytic efficiency is comparatively
high for CuAg BMPs. Furthermore, the antibacterial assay is carried
out, and Ag NPs display effective antibacterial activity against
Klebsiella pneumoniae
,
Salmonella
ser.
Typhimurium,
Acinetobacter baumannii
,
Shigella
flexneri
, and
Pseudomonas aeruginosa
.
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